1. Field of the Invention
The present invention relates to a routing table management method using an interface ID (identification) in the IPv6 (Internet Protocol version 6), and more particularly, to a routing table management method using an interface ID in the IPv6 that supports a RIPng (Routing Information Protocol for next generation), to prevent congestion in routing table management because of a multisource address, through managing a routing table using a different interface ID for each IPv6 router interface.
2. Description of the Related Art
Internet standard protocol, TCP/IP (Transport Control Protocol/Internet Protocol) of a computer, like other network protocols, has layered structure called protocol stack, protocol suite or simply protocol structure.
The TCP/IP protocol stack has two very important infrastructures, namely TCP and IP. The IP protocol corresponds to an OSI (Open Systems Interface) layer 3, and IPv4 is one of the most popular versions now. It is usually used to connect physical subnetworks and select a route to a destination IP address.
To this end, the IP protocol provides source addresses and destination addresses of a number of internetworked terminals and nodes and does interpretation. The Internetwork layer being currently used employs a 32-bit IP address for intercommunication between hosts over a network. IP address distinguishes a specific node by using a network IP and a node IP (host IP).
As there has been an explosive increase in Internet use since 1990's, it became necessary to improve some weaknesses in the IPv4, including a shortage of allocable resources, lack of mobility, lack of security and so forth. To overcome these shortcomings, a new standard protocol, IPv6, was developed.
The IPv6, also called IPng (Internet Protocol next generation), is well described in RFC (Request for comments) 2460 standard document. Extending the length of an IP address from an existing 32 bits to 128 bits, the IPv6 protocol resolved the problem with the deficiency of Internet address resources, and provided a way to process multimedia data in real time. Unlike the IPv4 protocol in which a patch type protocol IPsec (Internet Protocol Security Protocol) was installed separately, the IPv6 protocol mounted the IP sec onto the protocol directly, thereby fortifying a security function even more.
However, IPv6 protocols and IPv4 protocols are not compatible to each other because their header structures are different. Supposedly in the near future IPv4 network will be replaced to one that can support IPv6 network or both the IPv4 and the IPv6 at the same time. In addition, the IPv6 protocol has been gradually expanding its application range through diverse test networks and part of commercial networks.
An IPv6 application TCP/IP standard protocol is composed of an application layer, a transport layer implemented of TCP or UDP (User Datagram Protocol), Internetwork layer implemented of IPv6 and/or ICMPv6 (Internet Control Message Protocol for IPv6), and a physical layer.
IPv6 Datagram, similar to the IPv4, is composed of two parts: Header and Payload. The payload transmits data between two hosts. IPv6 header has a fixed length of 40 bytes, and does not have a header checksum field that is known as a serious bottleneck phenomenon in the IPv4 protocol. More specifically, the header structure of the IPv6 protocol, unlike in the IPv4 protocol, is capable of supporting mobility and security, and providing quality assurance of the multimedia applications.
As for basic header fields of the IPv6 standard protocol, a 4-bit version field, an 8-bit traffic class field, a 20-bit stream label field in connection with QoS (Quality of Service), a 16-bit unsigned integer payload length field, an 8-bit NH (Next Header) defining type of a next header in the IPv6 header, an 8-bit unsigned integer hop field that decreases by ‘1’ each time from respective nodes forwarding a packet, a source address field representing a 128-bit address of a packet sender, and a destination address field representing a 128-bit address of a packet receiver.
Expanded header fields for implementing IPv6 more perfectly include a hop-by-hop option field, a destination option header, a routing header, a fragment header, an authentication header, an ESP (Encapsulating Security Payload) header and so on.
This type of IPv6 protocol is usually implemented in the form of software for PCs (personal computers). In general, it is adaptive to operating systems like WINDOWS, LINUX, REAL-TIME, or OS.
On the other hand, routing protocols can be divided into two kinds, namely IGP (Interior Gateway Protocol) and EGP (Exterior Gateway Protocol).
The IGP is a routing protocol used in one domain. Typical IGP protocols being currently used in the IPv4 include RIP (Routing Information Protocol), OSPF (Open Shortest Path First), IS-IS (Intermediate System to Intermediate System) and so forth.
The EGP is usually used for exchanging routing information between different domains, especially between ASs (autonomous systems). One of the typical EGP protocol for use in the IPv4 is BGP (Border Gateway Protocol).
The IGP transmits routing information within an AS while the EGP transmits routing information among more than one ASs.
In fact in a theoretical sense, the IPv6 routing technology is not much different from an existing IPv4 except that the IPv6, compared to the IPv4, sets forth more strict regulations on IPv6 addressing, e.g. route aggregation, and for this, an appropriate routing protocol should be designated and operated.
The following describes routing protocols supporting an already standardized IPv6 or an IPv6 in progress of standardization:                IGP protocols for use in IPv6                    RIPng            OSPFv6            IPv6 or IS-IS                        EGP protocol for use in IPv6                    BGP4+                        
RIP is the most frequently used IPv6 protocol implemented with a distance vector base algorithm.
Its definition was first given in 1988, and standardized by RFC 1058.
As aforementioned, the RIP is a protocol based on a distance vector algorithm. The protocol itself is very simple and was originally designed for small and medium sized networks. However, it has several defects as follows:
First, the longest route of the RIP is limited to a 15-hop network;
Second, the RIP undergoes a process called “counting unto infinity” for the purpose of solving a routing loop problem. Unfortunately this process consumes a great amount of network resources even before solving the problem; and
Third, the RIP does not consider real time parameters, e.g. delay, reliability or load, but uses a fixed measurement standard to compare alternate routes.
Following RFC 1723 (RIPv2), RFC 2080 (IPv6 supporting RIPng standard) defines the RIP protocol.
Although many algorithms for selecting an optimum source address are being studied to prevent the RIPng router from taking improper actions, the algorithms are all about selecting one of multiple addresses and designating it as a source address. Thus, if the source address is changed when selecting one according to the algorithm, the RIPng router is ended up with congestion again.